CARBOHYDRATES CONTAINING NITROGEN IN A FIVE-MEMBERED RING AND AN ATTEMPTED SYNTHESIS OF A CARBOHYDRATE WITH NITROGEN IN A SEVEN-MEMBERED RING

1965 ◽  
Vol 43 (8) ◽  
pp. 2345-2356 ◽  
Author(s):  
W. A. Szarek ◽  
J. K. N. Jones
Keyword(s):  
Mercuric Chloride ◽  
Acid Treatment ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
Lead Tetraacetate ◽  
Alkaline Degradation ◽  
Cadmium Carbonate

Lead tetraacetate oxidation of 6-acetamido-6-deoxy-D-galactose (IX) yielded a syrup which was converted to a compound formulated as 4-acetamido-4-deoxy-1,2-O-isopropylidene-D-threofuranose (XII). The same syrup was obtained by alkaline degradation of the product of oxidation of 5-acetamido-5-deoxy-D-xylose diethyl dithioacetal (XVII) with peroxypropionic acid. Treatment of compound XII with p-toluenesulfonyl chloride yielded crystalline 4-acetamido-4-deoxy-1,2-O-isopropylidene-3-O-p-tolylsufonyl-D-threofuranose (XIII).Demercaptalation of 6-acetamido-2,3,4,5-tetra-O-acetyl-6-deoxy-D-galactose diethyl dithioacetal (XX) with mercuric chloride and cadmium carbonate in aqueous acetone did not yield a nitrogen-containing septanose ring but an acyclic derivative.

scholarly journals Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

2014 ◽  
Vol 10 ◽  
pp. 2021-2026 ◽  
Author(s):  
Henning Hopf ◽  
Swaminathan Vijay Narayanan ◽  
Peter G Jones
Keyword(s):  
Structural Analysis ◽  
Spectroscopic Data ◽  
Acid Treatment ◽  
Aldol Condensation ◽  
Membered Ring ◽  
X Ray

Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18–20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21–23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring.

REACTIONS OF OXODELCOSINE AND INTERRELATION OF DELCOSINE AND DELSOLINE

1960 ◽  
Vol 38 (12) ◽  
pp. 2433-2440 ◽  
Author(s):  
Vinko Skarić ◽  
Léo Marion
Keyword(s):  
Sodium Borohydride ◽  
Membered Ring ◽  
Lead Tetraacetate ◽  
The Other ◽  
Supporting Evidence ◽  
Close Relationship ◽  
Suggested Structure ◽  
Hydrolysis Of

The oxidation of diacetyldelcosine produces a lactam which, after hydrolysis of the acetyl groups, can be oxidized further to a diketo-lactam in which one of the keto groups is in a five- and the other in a six-membered ring. This result leads to an alteration of the previously suggested structure of delcosine. The new structure suggests a close relationship between delcosine and delsoline which is confirmed by the methylation of the former. The reaction is selective and gives rise to a monomethyldelcosine identical in every way with delsoline. Reduction of the diketo-lactam (didehydro-oxodelcosine) with sodium borohydride gives oxodelcosine. Dehydro-oxodelcosine is also described, and its oxidation with lead tetraacetate as well as that of oxodelcosine lead to the formation of keto-products which lend supporting evidence for the structure assigned to delcosine.

The effect of pressure on cyclic reactions

1967 ◽  
Vol 20 (7) ◽  
pp. 1335 ◽  
Author(s):  
AH Ewald ◽  
DJ Ottley
Keyword(s):  
Transition States ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
Effect Of Pressure ◽  
Cyclic Reaction

Rates of the cyclization of 4-chlorobutanol and of some analogous non- cyclic solvolysis reactions have been measured in water, methanol, and aqueous acetone at pressures up to 3000 atm. The volume of activation of the cyclic reaction is less negative than those of the linear reactions, in each solvent, but it is suggested that the transition states of both types of reaction may be solvated to about the same extent. The volume of activation for the formation of an eight-membered ring in the cyclization of 4-bromobutylcatechol monoether was also determined.

ELECTROPHILIC CATALYSIS IN SOLVOLYTIC REACTIONS: VII. SOLVENT EFFECT

1965 ◽  
Vol 43 (6) ◽  
pp. 1770-1777 ◽  
Author(s):  
R. Anantaraman ◽  
K. Saramma
Keyword(s):  
Solvent Effect ◽  
Mercuric Chloride ◽  
Aqueous Ethanol ◽  
Chloride Ions ◽  
Aqueous Acetone ◽  
Normal Reaction ◽  
Suggested Explanation

The rates of mercuric chloride catalyzed solvolysis of some alkyl chlorides in aqueous acetone and ethanol solvents have been compared. It is found that the increase in rate on changing from the acetone to the ethanol solvent is less in the catalyzed than in the normal reaction. On the basis that the electrophilic activity of the catalyst is less in aqueous ethanol than in aqueous acetone an explanation for the anomaly has been suggested. The effect, on the rates of solvolysis, of added chloride ions is in accord with the suggested explanation.

scholarly journals The Conformation of a Nine-membered Ring. Crystal Structure of the 1:1 Addition Compound Mercuric Chloride-Cyclononanone.

1971 ◽  
Vol 25 ◽  
pp. 1114-1124 ◽  
Author(s):  
S. Dahl ◽  
P. Groth ◽  
Manohar Singh Sood ◽  
Bent Eichstedt Nielsen ◽  
Hans Ljunggren ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mercuric Chloride ◽  
Membered Ring ◽  
Addition Compound

The crystal and molecular structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate

1985 ◽  
Vol 63 (4) ◽  
pp. 862-865 ◽  
Author(s):  
Judith C. Gallucci ◽  
Katsuo Ohkata ◽  
Leo A. Paquette
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Molecular Geometry ◽  
Chair Conformation ◽  
Membered Ring ◽  
Aqueous Acetone ◽  
X Ray Diffraction ◽  
X Ray ◽  
R Value

The crystal structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate, 2, has been determined by single crystal X-ray diffraction and refined to an R value of 0.051. The crystal structure is triclinic with a = 10.208(2), b = 13.355(2), c = 7.068(1) Å, α = 99.35(1)°, β = 100.63(1)°, γ = 100.79(1)°, and the space group is [Formula: see text] with two molecules per cell, D(calcd) = 1.39 g cm−3. The unsaturated five-membered ring resides in an envelope conformation with C6—C11—C12—C13 lying essentially in a plane. The fifth atom, C1, is positioned 0.47 Å out of this plane on the side opposite O1. The latter is situated 1.38 Å away and projects the 3,5-dinitrobenzoate group above the central portion of the cyclohexadiene unit. Four contiguous carbon atoms in the latter ring are mutually coplanar and the fused cyclohexane ring adopts a chair conformation. The overall molecular geometry is reconcilable with its solvolytic behavior in aqueous acetone.

ELECTROPHILIC CATALYSIS IN SOLVOLYTIC REACTIONS: IX. INDUCTOMERIC EFFECT

1966 ◽  
Vol 44 (20) ◽  
pp. 2415-2419 ◽  
Author(s):  
R. Anantaraman ◽  
M. R. Nair
Keyword(s):  
Mercuric Chloride ◽  
Aqueous Ethanol ◽  
Chloride Ions ◽  
Aqueous Acetone ◽  
Rate Of Hydrolysis ◽  
Presence And Absence ◽  
Catalyzed Reactions

The rates of solvolysis of 1-(p-alkylphenyl)ethyl chlorides (Alk = Me, Et, i-Pr, and t-Bu) in the presence and absence of mercuric chloride have been measured in aqueous acetone and ethanol solvents. In all cases, the Baker–Nathan order is followed. For all normal reactions and for the catalyzed reactions in 90% aqueous acetone and 90% aqueous ethanol there is an increase in the heats and entropies of activation as the series is ascended, while for the catalyzed reaction in 75% and 80% aqueous acetone, there is a decrease. It is suggested that in the more aqueous acetone solvents the catalyst calls into play an inductomeric effect. The effect of added chloride ions on the rate of hydrolysis has been studied and the results are discussed.

scholarly journals RING CONTRACTION DURING THE LEAD TETRAACETATE OXIDATION OF REDUCING SUGARS

1964 ◽  
Vol 42 (11) ◽  
pp. 2365-2374 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Reducing Sugars ◽  
Acyl Migration ◽  
Large Change ◽  
High Reactivity ◽  
Membered Ring ◽  
Lead Tetraacetate ◽  
The Other ◽  
Concentration Change ◽  
Pyranose Form ◽  
Cleavage Step

The rate of oxidation of D-glucose by lead tetraacetate in acetic acid is affected little by a large change in concentration of reactants, showing that the glycol cleavage step is not rate-controlling. Oxidation of 3-O-methyl-6-O-trityl-D-glucose yields 3-O-formyl-2-O-methyl-5-O-trityl-D-arabinose; the latter is not derived by production initially of a 4-O-formyl derivative that undergoes acyl migration. It is probable that the oxidation of D-glucose proceeds with conversion of the pyranose sugar into a furanose intermediate. By contrast, D-mannose appears to be oxidized mainly in the pyranose form, as shown by the oxidation patterns of D-mannose-1- and -2-14C and 5-O-methyl-D-mannofuranose, and the effects of concentration change on the reaction of D-mannose and derivatives. The proximity of the ring oxygen atom to the 1,2-diol group may contribute to the unusually high reactivity of D-mannopyranose as compared with other types of monocyclic six-membered ring vic-diols.Intermediate proportions of furanose and pyranose pathways characterize the lead tetraacetate oxidation of the other six aldohexoses. Similarities in the behavior of glucose and idose, gulose and mannose, and allose and talose may originate in steric similarities between these pairs of sugars.

Fasciaton of Pectate Elementary Fibrils

1973 ◽  
Vol 31 ◽  
pp. 60-61
Author(s):  
George F. Leeper
Keyword(s):  
Acid Treatment ◽  
Carbon Film ◽  
Final Concentration ◽  
Cellulose Microfibrils ◽  
Pectic Acid ◽  
Elementary Fibrils

Polysaccharide elementary fibrils are usually fasciated into microfibrils of from one hundred to a few hundred Angstroms wide. Cellulose microfibrils when subjected to acid treatment dissociate into component elementary fibrils. For pectic acid it was observed that variations in pH could cause a change in the fasciation of the elementary fibrils.Solutions of purified pectic acid and sodium phosphotungtate were adjusted to various pH levels with NaOH or HCl and diluted to give a final concentration of 0.5 and 1% for the polysaccharide and negative stains respectively. Micrographs were made of the samples after drying on a carbon film covered grid. The average number of elementary fibrils was determined by counting the number of elementary fibrils in each fascicle intersected by lines drawn across the micrograph.

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